Análisis de errores en tareas sobre el concepto de derivada : una mirada desde la teoría APOE (Acción, Proceso, Objeto, y Esquema)

Funding Information: Este trabajo desarrollado gracias a la Agencia Nacional de Investigación y Desarrollo (ANID) por medio del proyecto N°11180899 y la colaboración de la Facultad de Ciencias de la Ingeniería de la UACh.Este estudio se enfoca en lo visible, es decir, en el análisis de errores que los estudiantes cometen a fin de identificar posibles dificultades. Se considera el marco propuesto por la teoría APOE (Acción, Proceso, Objeto, y Esquema), por medio de la definición de 27 variables en función de elementos matemáticos involucrados en tres tareas que conforman un cuestionario sobre el concepto de derivada. Los participantes son 103 estudiantes de primer año de ingeniería. Los datos corresponden a las producciones de los estudiantes, obtenidos de la aplicación del cuestionario y recolectados durante el primer semestre del año 2021. Los resultados muestran que existen dificultades asociadas a la construcción de la reversión de procesos que se manifiesta en el gran número de errores asociados al uso de las variables que se establecen a partir de las equivalencias lógicas. Se concluye que la encapsulación de la derivada como un objeto cognitivo, correspondiente a una función, es compleja de alcanzar.The present study focuses on the visible, that is, on analyzing errors that students make to identify possible causes. The framework proposed by the APOE (Action, Process, Object, and Schema) theory is applied through the definition of 27 variables based on mathematical elements involved in three tasks that conform a questionnaire on the concept of derivative. The participants are 103 first-year engineering students. The data gathered consist of students' answers to the questionnaire collected during the first semester of the year 2021. The results show that there are difficulties associated with the construction of the reversal of processes as revealed by the great number of errors associated with the use variables obtained from logical equivalences. It is concluded that encapsulating the derivative as a cognitive object, corresponding to its function, is difficult to achieve

Interferencia del Herpesvirus equino 1 (EHV-1) en la apoptosis inducida

La apoptosis es un tipo de muerte celular programada que puede ser desencadenada por múltiples factores, tanto internos como externos; dentro de estos últimos se encuentran las infecciones virales. Algunos alphaherpesvirus han desarrollado diversas estrategias para retardar o inhibir la muerte celular obteniendo, de esta manera, su propio beneficio al poder permanecer durante más tiempo en la célula. Hasta el momento no se ha identificado ningún mecanismo relacionado con la modulación de la muerte celular durante la infección con Herpesvirus equino tipo 1 (EHV-1). El objetivo del presente trabajo fue describir el efecto producido por la infección con EHV-1 sobre cultivos celulares inducidos a la muerte por apoptosis. La evaluación de la apoptosis se realizó mediante el reconocimiento de la fragmentación en escalera del ADN, la evaluación de la relación Anexina V/ioduro de propidio (IP) y la determinación del clivaje de la citoqueratina 18, utilizando técnicas de inmunofluorescencia. Los resultados indican una posible interferencia del EHV-1 con la muerte por apoptosis hacia la mitad de su ciclo de replicación, que se incrementa hacia el final del mismo.Apoptosis is a programmed cell death that can be triggered by many factors, both internal and external. Viral infections are included among the latter. Some alphaherpesvirus have developed several strategies to retard or inhibit cell death and thus the virus benefits itself by staying longer in the cell. So far, no mechanisms have been identified related to modulation of cell death during infection with equine herpesvirus type 1 (EHV-1). The aim of the present study was to describe the effect produced by the infection with EHV-1 on apoptosis-induced cell cultures. Assessment of apoptosis was performed by DNA laddering, the Annexin V/propidium iodide (PI) determination and the cytokeratin 18 cleavage analysis using immunofluorescence techniques. Results indicate a possible interference of EHV-1 with apoptotic cell death in the middle of its replication cycle, being increased by its end

c-Abl tyrosine kinase down-regulation as target for memory improvement in Alzheimer’s disease

BackgroundGrowing evidence suggests that the non-receptor tyrosine kinase, c-Abl, plays a significant role in the pathogenesis of Alzheimer’s disease (AD). Here, we analyzed the effect of c-Abl on the cognitive performance decline of APPSwe/PSEN1ΔE9 (APP/PS1) mouse model for AD.MethodsWe used the conditional genetic ablation of c-Abl in the brain (c-Abl-KO) and pharmacological treatment with neurotinib, a novel allosteric c-Abl inhibitor with high brain penetrance, imbued in rodent’s chow.ResultsWe found that APP/PS1/c-Abl-KO mice and APP/PS1 neurotinib-fed mice had improved performance in hippocampus-dependent tasks. In the object location and Barnes-maze tests, they recognized the displaced object and learned the location of the escape hole faster than APP/PS1 mice. Also, APP/PS1 neurotinib-fed mice required fewer trials to reach the learning criterion in the memory flexibility test. Accordingly, c-Abl absence and inhibition caused fewer amyloid plaques, reduced astrogliosis, and preserved neurons in the hippocampus.DiscussionOur results further validate c-Abl as a target for AD, and the neurotinib, a novel c-Abl inhibitor, as a suitable preclinical candidate for AD therapies

Modelos experimentales para el estudio de la patogenia de la muerte embrionaria en tricomonosis bovina y herpesvirosis equina

Desde hace mucho tiempo, por razones prácticas, científicas y éticas, se han desarrollado modelos experimentales con animales de laboratorio para su aplicación en investigaciones biomédicas. Los modelos animales se definen como “organismos vivientes con una inherente adquisición natural a procesos patológicos inducidos o espontáneos que, de una u otra manera, semejan el mismo fenómeno ocurrido en el hospedador natural” (Márquez, 1997). Los animales de laboratorio son modelos muy convenientes y herramientas útiles para utilizar en el estudio de muchas enfermedades infecciosas. En el caso de medicina veterinaria, en especial cuando se trata de enfermedades de grandes animales, el uso del hospedador natural para estudiar aspectos patogénicos e inmunológicos de una infección, muchas veces se torna dificultoso, tanto por las inconveniencias que genera el manejo de estos animales como por el costo que implica. Debido al interés y la complejidad en el estudio de las enfermedades infecciosas, hay una búsqueda en la profundización de los conocimientos del proceso intrínseco de la inmunopatogenia que requiere de la creación de modelos animales alternativos a los hospedadores naturales. El objetivo es generar diseños experimentales confiables y reproducibles, desarrollables en medios controlados en espacios reducidos y con menor costo. Entre las múltiples ventajas que derivan de la utilización de modelos experimentales en el estudio de diferentes enfermedades, se mencionan las siguientes como las más importantes: • Conocer la historia natural de la enfermedad, cuya etiología, patogenia, sintomatología y evolución pueden mantenerse en condiciones experimentales, sin la influencia de factores extraños que la modifiquen. • Reproducir la enfermedad en forma experimental, casi a voluntad, lo que permite disponer de la casuística necesaria. • Realizar estudios fisiopatológicos, desarrollando nuevas técnicas diagnósticas para tal enfermedad. • Estudiar las enfermedades en animales endocriados lo que permite un amplio campo de investigación en inmunología, patología y genética, entre otras áreas (Cuba Caparó, 1982). En la selección de la especie utilizada como modelo animal es importante tener en cuenta algunas características generales: a) que permita la transferencia de la información, b) bajo costo y disponibilidad permanentes, c) generalización de los resultados, d) facilidad y adaptabilidad a la manipulación experimental, e) que se pueda contar con un número de animales necesarios para realizar el experimento, f) tiempo de vida, edad en que se alcanza la adultez y generación del número de progenies necesarias en poco tiempo, g) consecuencias ecológicas e implicancias éticas de su uso (Klein, 2000).Incluye las palabras de presentación del proyecto a cargo del Dr. Carlos O. Scoppa.Academia Nacional de Agronomía y Veterinari

Errores sobre subespacios vectoriales : un estudio exploratorio con estudiantes de primer año de ingeniería

Esta investigación exploratoria identifica y clasifica errores vinculados al concepto de subespacio vectorial que cometen estudiantes de ingeniería de primer año de universidad. Para ello, 210 estudiantes identifican y justifican por escrito por qué un conjunto no es un subespacio vectorial. Los resultados muestran que los estudiantes cometen tres tipos errores (E1, E2, E3): 1) procedimiento incorrecto para determinar si un conjunto es subespacio vectorial, 2) relaciones incoherentes entre conceptos y 3) representación errónea de los elementos de un subespacio vectorial. Esta tipología puede ser una guía para diseñar tareas que promuevan la comprensión de este concepto y gestionar la emergencia de estos errores en el aula. Se concluye que la clasificación de errores sobre subespacio vectorial puede ayudar a los profesores a la hora de planificar la enseñanza de este concepto.This exploratory research study identifies and classifies errors on the concept of vector subspace that are committed by first-year engineering students. Two-hundred and ten students identify and justify in writing why a set is not a vector subspace. The results show that students committed three types of errors (E1, E2, and E3): 1) conducting an incorrect procedure when determining whether a set is a vector subspace, 2) inferring incoherent correlations between concepts, and 3) misrepresenting vector subspace elements. This typology can be used as a guide to design tasks that enhance the understanding of the vector subspace concept. It can also serve to determine when these types of errors emerge in the classroom. It is concluded that classifying student errors on the concept of vector subspace can assist professors when planning on how to teach this concept

Unsymmetrical cyrhetrenyl and ferrocenyl azines derived from 5-nitrofurane: Synthesis, structural characterization and electrochemistry

A new series of unsymmetrical cyrhetrenyl and ferrocenyl azines that were monosubstituted [(η5-C5H4)-C(R)=N-N=CH(5-NO2-2-C4H2O)]M {with M=Re(CO)3 and R=H (1a) or R=Me (1b); M=Fe(η5-C5H5) and R=H (2a) or R=Me (2b)} and disubstituted [Fe{(η5-C5H4)-C(Me)=N-N=CH(5-NO2-2-C4H2O)}2] (3a) were prepared by condensation reactions of the corresponding organometallic hydrazone [(η5-C5H4)-C(R)=N-NH2)]M with 5-nitro-2-furaldehyde. The 1H and 13C{1H} NMR spectra indicated that these compounds adopted an (E,E)-configuration about the 〉C=N - bond and an s-trans conformation about the N1-N2 bond, and this result was confirmed by X-ray crystallographic analyses of 1a and 2b. The opposite electronic effects of the organometallic fragments correlate with the co-planarity of the [(η5-C5H4)-C(R)=N-N=CH(5-NO2-2-C4H2O)] system, the reduction potential of the nitro group (E1/2) and the chemical shifts of the iminic carbons.A.H.K. wishes to acknowledge FONDECYT-Chile (Projects 1150601 and 1110669) and D.I. Pontificia Universidad Católica de Valparaíso. J.G. wishes to acknowledge CONICYT and DEA for a Doctoral scholarship and D.I.-PUCV

Ferrocenyl and cyrhetrenyl azines containing a 5-nitroheterocyclic moiety: synthesis, structural characterization, electrochemistry and evaluation as anti-Trypanosoma cruzi agents

The synthesis of unsymmetrical ferrocenyl and cyrhetrenyl azines [(η-CH)-CR=N-N=CH-2-CHX-5-NO]M (M=Re(CO), Fe(η-CH); R = H, CH, X = O, S) has led to the development of new derivatives of 5-nitroheterocycles as potential anti-trypanosomal agents. The structures of compounds have been confirmed using conventional spectroscopic techniques (FT-IR, H and C NMR), mass spectrometry, including single-crystal X-ray diffraction analysis of compounds 2NT and 4NT. Based on the chemical shifts of the iminic carbons (C, C) and the reduction potential of the nitro group (E), an extensive π-conjugation of the azine bridge (-C(R)=N-N=CH-) was observed along with a correlation between the opposing electronic effects of the cyrhetrenyl and ferrocenyl fragments. It was established that the existence of an electron-withdrawing group (cyrhetrene) could facilitate the generation of radical species (RNO to RNO ) through the azine bridge. The organometallic azines were evaluated for anti-trypanosomal activity in vitro against the epimastigote form of the Dm28c strain of T. cruzi, yielding IC values in the low micromolar range.A.H.K. wishes to acknowledge FONDECYT-Chile (Projects 1150601 and 1110669), FONDEQUIP (Project EQM 130154) and D.I. Pontificia Universidad Católica de Valparaíso; J.G. wishes to acknowledge CONICYT and D.I. Pontificia Universidad Católica de Valparaíso for a postdoctoral position

Understanding the Role of ATP Release through Connexins Hemichannels during Neurulation

Neurulation is a crucial process in the formation of the central nervous system (CNS), which begins with the folding and fusion of the neural plate, leading to the generation of the neural tube and subsequent development of the brain and spinal cord. Environmental and genetic factors that interfere with the neurulation process promote neural tube defects (NTDs). Connexins (Cxs) are transmembrane proteins that form gap junctions (GJs) and hemichannels (HCs) in vertebrates, allowing cell-cell (GJ) or paracrine (HCs) communication through the release of ATP, glutamate, and NAD+; regulating processes such as cell migration and synaptic transmission. Changes in the state of phosphorylation and/or the intracellular redox potential activate the opening of HCs in different cell types. Cxs such as Cx43 and Cx32 have been associated with proliferation and migration at different stages of CNS development. Here, using molecular and cellular biology techniques (permeability), we demonstrate the expression and functionality of HCs-Cxs, including Cx46 and Cx32, which are associated with the release of ATP during the neurulation process in Xenopus laevis. Furthermore, applications of FGF2 and/or changes in intracellular redox potentials (DTT), well known HCs-Cxs modulators, transiently regulated the ATP release in our model. Importantly, the blockade of HCs-Cxs by carbenoxolone (CBX) and enoxolone (ENX) reduced ATP release with a concomitant formation of NTDs. We propose two possible and highly conserved binding sites (N and E) in Cx46 that may mediate the pharmacological effect of CBX and ENX on the formation of NTDs. In summary, our results highlight the importance of ATP release mediated by HCs-Cxs during neurulation

Understanding the Role of ATP Release through Connexins Hemichannels during Neurulation

Neurulation is a crucial process in the formation of the central nervous system (CNS), which begins with the folding and fusion of the neural plate, leading to the generation of the neural tube and subsequent development of the brain and spinal cord. Environmental and genetic factors that interfere with the neurulation process promote neural tube defects (NTDs). Connexins (Cxs) are transmembrane proteins that form gap junctions (GJs) and hemichannels (HCs) in vertebrates, allowing cell-cell (GJ) or paracrine (HCs) communication through the release of ATP, glutamate, and NAD+; regulating processes such as cell migration and synaptic transmission. Changes in the state of phosphorylation and/or the intracellular redox potential activate the opening of HCs in different cell types. Cxs such as Cx43 and Cx32 have been associated with proliferation and migration at different stages of CNS development. Here, using molecular and cellular biology techniques (permeability), we demonstrate the expression and functionality of HCs-Cxs, including Cx46 and Cx32, which are associated with the release of ATP during the neurulation process in Xenopus laevis. Furthermore, applications of FGF2 and/or changes in intracellular redox potentials (DTT), well known HCs-Cxs modulators, transiently regulated the ATP release in our model. Importantly, the blockade of HCs-Cxs by carbenoxolone (CBX) and enoxolone (ENX) reduced ATP release with a concomitant formation of NTDs. We propose two possible and highly conserved binding sites (N and E) in Cx46 that may mediate the pharmacological effect of CBX and ENX on the formation of NTDs. In summary, our results highlight the importance of ATP release mediated by HCs-Cxs during neurulation